Abstract
BackgroundThe study aimed to establish quantitative diagnostic criteria for rapidly progressive osteoarthritis (RPOA) of the hip and to compare the criteria with those for other pathological hip entities in the Asian population.MethodsFrom July 2011 to September 2019, 126 patients who had undergone hip replacement were retrospectively recruited from a fast-track joint replacement list. Patient demographics and radiological parameters were evaluated. Diagnosis of hip RPOA was established based on Lequesne et al’s criteria. The patients with RPOA, hip dysplasia, avascular necrosis, and primary osteoarthritis were allocated to the corresponding groups separately and compared. The diagnostic criteria of RPOA were established and validated in the sample population.ResultsDiagnosis of hip RPOA was confirmed in 18 patients. Their mean age at surgery (72 years) was significantly higher in this group than in the dysplasia and avascular necrosis groups. The mean pelvic tilt parameter (0.485) of RPOA group was significantly lower than those of other groups. The mean initial Tonnis angle (8.35°) of RPOA group was significantly higher than those of avascular necrosis and osteoarthritis groups. The differences were statistically significant between RPOA and non-RPOA groups in limb shortening rate, superior joint space narrowing, acetabular destruction, and head destruction (P < 0.05). Tonnis angle and lateral subluxation also increased significantly during the disease progression.ConclusionPosterior pelvic tilt and increased Tonnis angle may contribute to the pathogenesis of RPOA, leading to progressive acquired acetabular obliquity and lateral subluxation. We propose the modern comprehensive diagnostic criteria be based on the existing literature and the current findings. Further external validation is recommended.
Highlights
Rapidly progressive osteoarthritis (RPOA) of the hip, known as rapidly destructive osteoarthritis of hip, is a rare pathological condition manifesting as rapid chondrolysis (Type 1 rapidly progressive osteoarthritis (RPOA)) followed by hip joint destruction (Type 2 RPOA)
The diagnosis established based on these diagnostic criteria entails observation for a long period of time
Diagnoses other than RPOA were categorized into (1) hip dysplasia with an initial Wiberg angle of less than 25 degrees, or a Tonnis angle of more than 10 degrees [9]; (2) radiographic avascular necrosis (AVN) characterized by femoral head lucency, sclerosis, or flattening before joint space narrowing; and (3) primary osteoarthritis with osteophytes and gradual joint space narrowing as the predominant radiological features
Summary
Progressive osteoarthritis (RPOA) of the hip, known as rapidly destructive osteoarthritis of hip, is a rare pathological condition manifesting as rapid chondrolysis (Type 1 RPOA) followed by hip joint destruction (Type 2 RPOA). The reported incidence of RPOA is 16, and 10% of total hip arthroplasties fulfilled the diagnosis. Lequesne et al [4] proposed the first and most popularly adopted diagnostic criteria, including progressive chondrolysis exceeding 2 mm per year or the loss of more than 50% joint space within 1 year. The diagnosis established based on these diagnostic criteria entails observation for a long period of time. The study aimed to establish quantitative diagnostic criteria for rapidly progressive osteoarthritis (RPOA) of the hip and to compare the criteria with those for other pathological hip entities in the Asian population
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